s1_generate_a_series_of_files(){
  for i in {1..100}; do
	  echo -n  "$i" > "/tmp/new_file$i"
  done
}
s2_list_4_files_in_long_format_about_account_and_group(){
   ls -l /etc/passwd /etc/group /etc/shadow /etc/gshadow | sort
}
s3_find_items_related_to_given_username(){
   { grep -h "^$1:" /etc/passwd /etc/shadow 2>/dev/null || true;} | sort
}
s4_find_items_related_to_given_group_name(){
   local groupname="$1"
   grep -h "^$groupname:" /etc/group /etc/gshadow | sort
}
s5_create_groups_for_given_group_names(){
   groupadd rnd
   groupadd itoperation
}
s6_create_users_and_set_their_group_as_required(){
   useradd -G rnd adam
   useradd -G rnd bob
   useradd -G itoperation calvin
   useradd -G itoperation david
   useradd -G rnd edward
}
s7_change_users_shell(){
  chsh -s /usr/bin/sh adam
  chsh -s /usr/bin/sh edward
}
s8_set_password_change_policy(){
  for user in adam bob calvin david edward;  do
	 chage -m 10 -M 60 -W 10 "$user"
  done 
}
s9_set_password_for_five_users(){
  local usernames=(adam bob calvin david edward)
  for i in $(seq 1 5); do
	  echo "${usernames[$((i-1))]}:${!i}"

  done | chpasswd
}
s10_lock_bobs_password(){
   passwd -l bob
}
s11_include_adam_into_wheel_group(){
   usermod -aG wheel adam
}
s12_change_files_permission(){
   for i in $(seq 3 3 99); do
      chmod 640 "/tmp/new_file$i"  
   done
}
